TCR Signaling

The T-Cell Receptor is a protein complex on the surface of T-cell responsible for antigen recognition. The activation induces a number of signaling cascades finally leading to the transcription of several gene products which allow the T cells to differentiate, proliferate and secrete a number of cytokines.

Signaling proteins like SLP-76 can now dock to LAT and gets phosporylated by ZAP-70 as well3. SLP-76 promotes recruitment of Vav (GEF), the adaptor proteins NCK and GADS, and an inducible T cell kinase (Itk). Ltk enables PLCγ1 by phosphorylation which leads to hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) to produce the second messengers diacylglycerol (DAG) and inositol trisphosphate (IP3).

The signal cascades are regulated on several occasions to diversify the cell answer. Extracellular signals are recognized by additional cell surface receptors like CD28 or LFA-1 and further regulate cellular response.

References:

Braiman, A and Isakov, N (2015): "The Role of Crk Adaptor Proteins in T-Cell Adhesion and Migration”. Front. Immunol., v.6,2015. [PMID: 4593252]

Receptor and Membrane Proteins

CD28 (CD28):

The protein encoded by this gene is essential for T-cell proliferation and survival, cytokine production, and T-helper type-2 development. Several alternatively spliced transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Jul 2011].
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